The Japanese prefix '高 (こう)' means 'high'. It is commonly used in compound words to indicate something of high quality, high level, or high degree. For example: high school「高校」(こうこう), high price「高価」(こうか), high temperature「高温」(こうおん). This prefix is often used in technical or formal contexts to denote superiority or elevation in status, quality, or quantity. It is important to note that '高' as a prefix is read as 'こう' and is different from the standalone kanji '高' which can have other readings and meanings.